If there is less quantity of something available, then the price goes up, that's economics 101. And flashcart hardware is pretty much mainstream anymore. I actually know a guy IRL who visits the site here at school for technical help.
I think it's a good deal, It always bothered me that I couldn't play GB/GBC games off my G6 Flash without using Goomba (cause of the voltage problem). The price is really not high, my G6 Flash 4G and Passcard 3 cost like $100 less than 4 years ago.